1. Field of the Invention
The present invention relates to a signal detection circuit having a deglitch function, and a method thereof. More particularly, the present invention relates to a signal detection circuit for detecting signal squelch of a differential signal and for deglitch, and a method thereof.
2. Description of Related Art
In signal transceiving mechanism of serial link, a signal detector is generally allocated on the receiving side for detecting the differential input signal and judging whether the input signal is a required one and whether its amplitude is complied with a predefined signal specification according to a reference voltage.
Sometimes, the input signal received is greater than the reference voltage. Therefore, the signal detector is preferably to have a rectification function. Moreover, during the signal transition, the differential signal will be less than the reference voltage within a very short period of time, which may cause a glitch in the judgment of the signal squelch. In addition, noise may also cause a glitch.
FIG. 1 is a structural diagram of a conventional low voltage differential signal detector. Referring to FIG. 1, the signal detector 10 includes subtracters 11 and 12, a reference voltage generator 13, samplers 14 and 15, a clock generator 16, an OR logic gate 17, and a pulse stretcher 18.
The subtracters 11 and 12 subtract the reference voltage VREF (generated from the reference voltage generator 13) from the input signal IN, and output the result to the samplers 14 and 15. The samplers 14 and 15 sample output signals of the subtracters 11 and 12 according to a reference clock generated from the clock generator 16, and output the sampling results to the OR logic gate 17. The samplers 14 and 15 may amplify the output signal of the subtracters 11 and 12. The clock generator 16 may randomly generate a low frequency reference clock. Therefore, the sampling points of the samplers 14 and 15 are random.
The pulse stretcher 18 stretches the pulse width of the output signal of the OR logic gate 17 to obtain an output signal OUT. Pulse width stretching helps following signal processing. In this conventional circuit, the samplers 14 and 15 and the OR logic gate 17 may achieve a full-wave rectification effect.
However, the samplers 14 and 15 must have a high gain for improving the common mode noise rejection capability of the conventional circuit. Moreover, the conventional circuit does not have a function of deglitch.
Therefore, a signal detection circuit for detecting differential signals is required to overcome the shortages of conventional circuits and provide some other advantages.